The invention relates generally to electrical cables and more particularly to an electrical cable having a bearing part and two concentrically arranged conductors.
Such electrical cables include a central, sheathed bearing part and two multiple-wire conductors wound on the bearing part which are disposed concentrically to one another. The two conductors are separated from each other by rubber insulation. Electrical cables formed from flexible electrical lines having a bearing part are primarily used to supply current to a mobile apparatus that uses electricity, such as a magnet in a lifting-magnet-type crane.
An electrical cable that supplies current to the pump of a bore-hole plant is disclosed in German Published Patent Application 31 25 164. This cable is comprised of three conductors arranged concentrically to one another. Each of the conductors is insulated and surrounded by a sheathing and a covering. A bearing part, which may be formed of plastic, is provided inside the first, central conductor. To assure that the cable is impermeable to water, bands made of an uncured elastomer may be provided above and below the conductor wires, which each form a stranded layer. To mechanically stabilize the cable, the conductors, which are arranged concentrically, have opposite directions of lay.
A flexible, electrical cable having a cable core which supplies current to a cutting machine is disclosed in German Published Patent Application 26 19 223. This cable has two concentrically disposed conductors. The individual wires of the inner conductor are twisted onto a rubber-sheathed bearing part made of steel stranded wires. The individual wires of the outer conductor are stranded onto the rubber insulation of the first conductor. A conductive rubber layer is extruded onto the second conductor.
The problem in the prior art is that there is no flexible electrical cable, which is tension-proof, capable of withstanding impacts and high dynamic stresses, and which is designed to supply current to a two-pole device.